filelib(3erl) Erlang Module Definition filelib(3erl)
NAME
filelib - File utilities, such as wildcard matching of filenames.
DESCRIPTION
This module contains utilities on a higher level than the file module.
This module does not support "raw" filenames (that is, files whose
names do not comply with the expected encoding). Such files are ignored
by the functions in this module.
For more information about raw filenames, see the file module.
Note:
Functionality in this module generally assumes valid input and does not
necessarily fail on input that does not use a valid encoding, but may
instead very likely produce invalid output.
File operations used to accept filenames containing null characters
(integer value zero). This caused the name to be truncated and in some
cases arguments to primitive operations to be mixed up. Filenames con-
taining null characters inside the filename are now rejected and will
cause primitive file operations to fail.
Warning:
Currently null characters at the end of the filename will be accepted
by primitive file operations. Such filenames are however still docu-
mented as invalid. The implementation will also change in the future
and reject such filenames.
DATA TYPES
filename() = file:name()
dirname() = filename()
dirname_all() = filename_all()
filename_all() = file:name_all()
find_file_rule() =
{ObjDirSuffix :: string(), SrcDirSuffix :: string()}
find_source_rule() =
{ObjExtension :: string(),
SrcExtension :: string(),
[find_file_rule()]}
EXPORTS
ensure_dir(Name) -> ok | {error, Reason}
Types:
Name = filename_all() | dirname_all()
Reason = file:posix()
Ensures that all parent directories for the specified file or
directory name Name exist, trying to create them if necessary.
Returns ok if all parent directories already exist or can be
created. Returns {error, Reason} if some parent directory does
not exist and cannot be created.
file_size(Filename) -> integer() >= 0
Types:
Filename = filename_all()
Returns the size of the specified file.
fold_files(Dir, RegExp, Recursive, Fun, AccIn) -> AccOut
Types:
Dir = dirname()
RegExp = string()
Recursive = boolean()
Fun = fun((F :: file:filename(), AccIn) -> AccOut)
AccIn = AccOut = term()
Folds function Fun over all (regular) files F in directory Dir
that match the regular expression RegExp (for a description of
the allowed regular expressions, see the re module). If Recur-
sive is true, all subdirectories to Dir are processed. The regu-
lar expression matching is only done on the filename without the
directory part.
If Unicode filename translation is in effect and the file system
is transparent, filenames that cannot be interpreted as Unicode
can be encountered, in which case the fun() must be prepared to
handle raw filenames (that is, binaries). If the regular expres-
sion contains codepoints > 255, it does not match filenames that
do not conform to the expected character encoding (that is, are
not encoded in valid UTF-8).
For more information about raw filenames, see the file module.
is_dir(Name) -> boolean()
Types:
Name = filename_all() | dirname_all()
Returns true if Name refers to a directory, otherwise false.
is_file(Name) -> boolean()
Types:
Name = filename_all() | dirname_all()
Returns true if Name refers to a file or a directory, otherwise
false.
is_regular(Name) -> boolean()
Types:
Name = filename_all()
Returns true if Name refers to a (regular) file, otherwise
false.
last_modified(Name) -> file:date_time() | 0
Types:
Name = filename_all() | dirname_all()
Returns the date and time the specified file or directory was
last modified, or 0 if the file does not exist.
wildcard(Wildcard) -> [file:filename()]
Types:
Wildcard = filename() | dirname()
Returns a list of all files that match Unix-style wildcard
string Wildcard.
The wildcard string looks like an ordinary filename, except that
the following "wildcard characters" are interpreted in a special
way:
?:
Matches one character.
*:
Matches any number of characters up to the end of the file-
name, the next dot, or the next slash.
**:
Two adjacent * used as a single pattern match all files and
zero or more directories and subdirectories.
[Character1,Character2,...]:
Matches any of the characters listed. Two characters sepa-
rated by a hyphen match a range of characters. Example: [A-
Z] matches any uppercase letter.
{Item,...}:
Alternation. Matches one of the alternatives.
Other characters represent themselves. Only filenames that have
exactly the same character in the same position match. Matching
is case-sensitive, for example, "a" does not match "A".
Directory separators must always be written as /, even on Win-
dows.
A character preceded by \ loses its special meaning. Note that \
must be written as \\ in a string literal. For example, "\\?*"
will match any filename starting with ?.
Notice that multiple "*" characters are allowed (as in Unix
wildcards, but opposed to Windows/DOS wildcards).
Examples:
The following examples assume that the current directory is the
top of an Erlang/OTP installation.
To find all .beam files in all applications, use the following
line:
filelib:wildcard("lib/*/ebin/*.beam").
To find .erl or .hrl in all applications src directories, use
either of the following lines:
filelib:wildcard("lib/*/src/*.?rl")
filelib:wildcard("lib/*/src/*.{erl,hrl}")
To find all .hrl files in src or include directories:
filelib:wildcard("lib/*/{src,include}/*.hrl").
To find all .erl or .hrl files in either src or include directo-
ries:
filelib:wildcard("lib/*/{src,include}/*.{erl,hrl}")
To find all .erl or .hrl files in any subdirectory:
filelib:wildcard("lib/**/*.{erl,hrl}")
wildcard(Wildcard, Cwd) -> [file:filename()]
Types:
Wildcard = filename() | dirname()
Cwd = dirname()
Same as wildcard/1, except that Cwd is used instead of the work-
ing directory.
find_file(Filename :: filename(), Dir :: filename()) ->
{ok, filename()} | {error, not_found}
find_file(Filename :: filename(),
Dir :: filename(),
Rules :: [find_file_rule()]) ->
{ok, filename()} | {error, not_found}
Looks for a file of the given name by applying suffix rules to
the given directory path. For example, a rule {"ebin", "src"}
means that if the directory path ends with "ebin", the corre-
sponding path ending in "src" should be searched.
If Rules is left out or is an empty list, the default system
rules are used. See also the Kernel application parameter
source_search_rules.
find_source(FilePath :: filename()) ->
{ok, filename()} | {error, not_found}
Equivalent to find_source(Base, Dir), where Dir is file-
name:dirname(FilePath) and Base is filename:basename(FilePath).
find_source(Filename :: filename(), Dir :: filename()) ->
{ok, filename()} | {error, not_found}
find_source(Filename :: filename(),
Dir :: filename(),
Rules :: [find_source_rule()]) ->
{ok, filename()} | {error, not_found}
Applies file extension specific rules to find the source file
for a given object file relative to the object directory. For
example, for a file with the extension .beam, the default rule
is to look for a file with a corresponding extension .erl by re-
placing the suffix "ebin" of the object directory path with
"src" or "src/*". The file search is done through find_file/3.
The directory of the object file is always tried before any
other directory specified by the rules.
If Rules is left out or is an empty list, the default system
rules are used. See also the Kernel application parameter
source_search_rules.
safe_relative_path(Filename, Cwd) -> unsafe | SafeFilename
Types:
Filename = Cwd = SafeFilename = filename_all()
Sanitizes the relative path by eliminating ".." and "." compo-
nents to protect against directory traversal attacks. Either re-
turns the sanitized path name, or the atom unsafe if the path is
unsafe. The path is considered unsafe in the following circum-
stances:
* The path is not relative.
* A ".." component would climb up above the root of the rela-
tive path.
* A symbolic link in the path points above the root of the
relative path.
Examples:
1> {ok, Cwd} = file:get_cwd().
...
2> filelib:safe_relative_path("dir/sub_dir/..", Cwd).
"dir"
3> filelib:safe_relative_path("dir/..", Cwd).
[]
4> filelib:safe_relative_path("dir/../..", Cwd).
unsafe
5> filelib:safe_relative_path("/abs/path", Cwd).
unsafe
Ericsson AB stdlib 3.13 filelib(3erl)